To reduce power consumption for all types of terminal device

ABSTRACT

A method of operating a terminal device and a plurality of network access nodes, wherein the method comprises: establishing first wake-up signalling configuration information for a first network access node; establishing second wake-up signalling configuration information for a second network access node; and monitoring for signalling transmitted by the first network access node in accordance with the first wake-up signalling format and monitoring for signalling transmitted by the second network access node in accordance with the second wake-up signalling format, and seeking to decode a subsequent paging message in response to detecting wake-up signalling in accordance with either the first wake-up signalling format or the second wake-up signalling format.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/763,995, filed May 14, 2020, which is based on PCT filingPCT/EP2018/081383, filed on Nov. 15, 2018, and claims priority to EP17201973.9, filed Nov. 15, 2017, the entire contents of each areincorporated herein by reference.

BACKGROUND Field

The present disclosure relates to telecommunications apparatus andmethods.

Description of Related Art

The “background” description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description which may nototherwise qualify as prior art at the time of filing, are neitherexpressly or impliedly admitted as prior art against the presentinvention.

Third and fourth generation mobile telecommunication systems, such asthose based on the 3GPP defined UMTS and Long Term Evolution (LTE)architecture, are able to support more sophisticated services thansimple voice and messaging services offered by previous generations ofmobile telecommunication systems. For example, with the improved radiointerface and enhanced data rates provided by LTE systems, a user isable to enjoy high data rate applications such as mobile video streamingand mobile video conferencing that would previously only have beenavailable via a fixed line data connection. The demand to deploy suchnetworks is therefore strong and the coverage area of these networks,i.e. geographic locations where access to the networks is possible, maybe expected to increase ever more rapidly.

Future wireless communications networks will be expected to routinelyand efficiently support communications with a wider range of devicesassociated with a wider range of data traffic profiles and types thancurrent systems are optimised to support. For example it is expectedfuture wireless communications networks will be expected to efficientlysupport communications with devices including reduced complexitydevices, machine type communication (MTC) devices, high resolution videodisplays, virtual reality headsets and so on. Some of these differenttypes of devices may be deployed in very large numbers, for example lowcomplexity devices for supporting the “The Internet of Things”, and maytypically be associated with the transmissions of relatively smallamounts of data with relatively high latency tolerance.

In view of this there is expected to be a desire for future wirelesscommunications networks, for example those which may be referred to as5G or new radio (NR) system/new radio access technology (RAT) systems,as well as future iterations/releases of existing systems, toefficiently support a wide range of devices associated with differentoperating characteristics, for example in terms of frequency ofcommunications and requirements for low power usage.

One example area of current interest in this regard includes theso-called “The Internet of Things”, or IoT for short. The 3GPP hasproposed in Release 13 of the 3GPP specifications to developtechnologies for supporting narrowband (NB)-IoT and so-called enhancedMTC (eMTC) operation using a LTE/4G wireless access interface andwireless infrastructure. More recently there have been proposals tobuild on these ideas in Release 14 of the 3GPP specifications withso-called enhanced NB-IoT (eNB-IoT) and further enhanced MTC (feMTC),and in Release 15 of the 3GPP specifications with so-called furtherenhanced NB-IoT (feNB-IoT) and even further enhanced MTC (efeMTC). See,for example, [1], [2], [3], [4]. At least some devices making use ofthese technologies are expected to be low complexity and inexpensivedevices requiring relatively infrequent communication of relatively lowbandwidth data. Low power consumption may be a particularly importantconsideration for these types of device, for example because they aresmall devices having correspondingly small batteries or because theyremotely located without ready access to external power. While a desirefor low power consumption may be a particularly important considerationfor such devices compared to other devices, it will nonetheless beappreciated that approaches that help reduce power consumption can beuseful for all types of terminal device.

SUMMARY

Respective aspects and features of the present disclosure are defined inthe appended claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, but are notrestrictive, of the present technology. The described embodiments,together with further advantages, will be best understood by referenceto the following detailed description taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings wherein likereference numerals designate identical or corresponding parts throughoutthe several views, and wherein:

FIG. 1 schematically represents some aspects of a LTE-type wirelesstelecommunication system which may be configured to operate inaccordance with certain embodiments of the present disclosure;

FIG. 2 schematically represents some aspects of a new radio accesstechnology (RAT) wireless telecommunications system which may beconfigured to operate in accordance with certain embodiments of thepresent disclosure;

FIGS. 3 and 4 schematically represent example time lines associated withpaging occasions in wireless telecommunication systems;

FIG. 5 schematically represents an example format for wake-up signalling(WUS) that may be used in certain embodiments of the disclosure;

FIG. 6 schematically represents some aspects of a wirelesstelecommunication system in accordance with certain embodiments of thepresent disclosure; and

FIGS. 7 and 8 are a signalling ladder diagrams (message sequence charts)schematically representing some operating aspects of wirelesstelecommunications systems in accordance with certain embodiments of thedisclosure.

DESCRIPTION OF EXAMPLE EMBODIMENTS

FIG. 1 provides a schematic diagram illustrating some basicfunctionality of a mobile telecommunications network/system 100operating generally in accordance with LTE principles, but which mayalso support other radio access technologies, and which may be adaptedto implement embodiments of the disclosure as described herein. Variouselements of FIG. 1 and certain aspects of their respective modes ofoperation are well-known and defined in the relevant standardsadministered by the 3GPP (RTM) body, and also described in many books onthe subject, for example, Holma H. and Toskala A [5]. It will beappreciated that operational aspects of the telecommunications networksdiscussed herein which are not specifically described (for example inrelation to specific communication protocols and physical channels forcommunicating between different elements) may be implemented inaccordance with any known techniques, for example according to therelevant standards and known proposed modifications and additions to therelevant standards.

The network 100 includes a plurality of base stations 101 connected to acore network 102. Each base station provides a coverage area 103 (i.e. acell) within which data can be communicated to and from terminal devices104. Data is transmitted from base stations 101 to terminal devices 104within their respective coverage areas 103 via a radio downlink. Data istransmitted from terminal devices 104 to the base stations 101 via aradio uplink. The core network 102 routes data to and from the terminaldevices 104 via the respective base stations 101 and provides functionssuch as authentication, mobility management, charging and so on.Terminal devices may also be referred to as mobile stations, userequipment (UE), user terminal, mobile radio, communications device, andso forth. Base stations, which are an example of network infrastructureequipment/network access node, may also be referred to as transceiverstations/nodeBs/e-nodeBs, g-nodeBs and so forth. In this regarddifferent terminology is often associated with different generations ofwireless telecommunications systems for elements providing broadlycomparable functionality. However, certain embodiments of the disclosuremay be equally implemented in different generations of wirelesstelecommunications systems, and for simplicity certain terminology maybe used regardless of the underlying network architecture. That is tosay, the use of a specific term in relation to certain exampleimplementations is not intended to indicate these implementations arelimited to a certain generation of network that may be most associatedwith that particular terminology.

FIG. 2 is a schematic diagram illustrating a network architecture for anew RAT wireless mobile telecommunications network/system 300 based onpreviously proposed approaches which may also be adapted to providefunctionality in accordance with embodiments of the disclosure describedherein. The new RAT network 300 represented in FIG. 2 comprises a firstcommunication cell 301 and a second communication cell 302. Eachcommunication cell 301, 302, comprises a controlling node (centralisedunit) 321, 322 in communication with a core network component 310 over arespective wired or wireless link 351, 352. The respective controllingnodes 321, 322 are also each in communication with a plurality ofdistributed units (radio access nodes/remote transmission and receptionpoints (TRPs)) 311, 312 in their respective cells. Again, thesecommunications may be over respective wired or wireless links. Thedistributed units 311, 312 are responsible for providing the radioaccess interface for terminal devices connected to the network. Eachdistributed unit 311, 312 has a coverage area (radio access footprint)341, 342 which together define the coverage of the respectivecommunication cells 301, 302. Each distributed unit 311, 312 includestransceiver circuitry 311 a, 312 a for transmission and reception ofwireless signals and processor circuitry 311 a, 311 b configured tocontrol the respective distributed units 311, 312.

In terms of broad top-level functionality, the core network component310 of the new RAT telecommunications system represented in FIG. 2 maybe broadly considered to correspond with the core network 102represented in FIG. 1, and the respective controlling nodes 321, 322 andtheir associated distributed units/TRPs 311, 312 may be broadlyconsidered to provide functionality corresponding to base stations ofFIG. 1. The term network infrastructure equipment/access node may beused to encompass these elements and more conventional base station typeelements of wireless telecommunications systems. Depending on theapplication at hand the responsibility for scheduling transmissionswhich are scheduled on the radio interface between the respectivedistributed units and the terminal devices may lie with the controllingnode/centralised unit and/or the distributed units/TRPs.

A terminal device 400 is represented in FIG. 2 within the coverage areaof the first communication cell 301. This terminal device 400 may thusexchange signalling with the first controlling node 321 in the firstcommunication cell via one of the distributed units 311 associated withthe first communication cell 301. In some cases communications for agiven terminal device are routed through only one of the distributedunits, but it will be appreciated in some other implementationscommunications associated with a given terminal device may be routedthrough more than one distributed unit, for example in a soft handoverscenario and other scenarios. The particular distributed unit(s) throughwhich a terminal device is currently connected through to the associatedcontrolling node may be referred to as active distributed units for theterminal device. Thus the active subset of distributed units for aterminal device may comprise one or more than one distributed unit(TRP). The controlling node 321 is responsible for determining which ofthe distributed units 311 spanning the first communication cell 301 isresponsible for radio communications with the terminal device 400 at anygiven time (i.e. which of the distributed units are currently activedistributed units for the terminal device). Typically this will be basedon measurements of radio channel conditions between the terminal device400 and respective ones of the distributed units 311. In this regard, itwill be appreciated the subset of the distributed units in a cell whichare currently active for a terminal device will depend, at least inpart, on the location of the terminal device within the cell (since thiscontributes significantly to the radio channel conditions that existbetween the terminal device and respective ones of the distributedunits).

In at least some implementations the involvement of the distributedunits in routing communications from the terminal device to acontrolling node (controlling unit) is transparent to the terminaldevice 400. That is to say, in some cases the terminal device may not beaware of which distributed unit is responsible for routingcommunications between the terminal device 400 and the controlling node321 of the communication cell 301 in which the terminal device iscurrently operating. In such cases, as far as the terminal device isconcerned, it simply transmits uplink data to the controlling node 321and receives downlink data from the controlling node 321 and theterminal device has no awareness of the involvement of the distributedunits 311. However, in other embodiments, a terminal device may be awareof which distributed unit(s) are involved in its communications.Switching and scheduling of the one or more distributed units may bedone at the network controlling node based on measurements by thedistributed units of the terminal device uplink signal or measurementstaken by the terminal device and reported to the controlling node viaone or more distributed units

In the example of FIG. 2, two communication cells 301, 302 and oneterminal device 400 are shown for simplicity, but it will of course beappreciated that in practice the system may comprise a larger number ofcommunication cells (each supported by a respective controlling node andplurality of distributed units) serving a larger number of terminaldevices.

It will further be appreciated that FIG. 2 represents merely one exampleof a proposed architecture for a new RAT telecommunications system inwhich approaches in accordance with the principles described herein maybe adopted, and the functionality disclosed herein may also be appliedin respect of wireless telecommunications systems having differentarchitectures.

Thus certain embodiments of the disclosure as discussed herein may beimplemented in wireless telecommunication systems/networks according tovarious different architectures, such as the example architectures shownin FIGS. 1 and 2. It will thus be appreciated the specific wirelesstelecommunications architecture in any given implementation is not ofprimary significance to the principles described herein. In this regard,certain embodiments of the disclosure may be described generally in thecontext of communications between network infrastructureequipment/access nodes and a terminal device, wherein the specificnature of the network infrastructure equipment/access node and theterminal device will depend on the network infrastructure for theimplementation at hand. For example, in some scenarios the networkinfrastructure equipment/access node may comprise a base station, suchas an LTE-type base station 101 as shown in FIG. 1 which is adapted toprovide functionality in accordance with the principles describedherein, and in other examples the network infrastructure equipment maycomprise a control unit/controlling node 321, 322 and/or a TRP 311, 312of the kind shown in FIG. 2 which is adapted to provide functionality inaccordance with the principles described herein.

As is well understood, various wireless telecommunications networks,such as the LTE-based network represented in FIG. 1 and the NR-basednetwork represented in FIG. 2, may support different Radio ResourceControl (RRC) modes for terminal devices, typically including: (i) RRCidle mode (RRC_IDLE); and (ii) RRC connected mode (RRC_CONNECTED). Whena terminal device transmits data, RRC connected mode is generally used.The RRC idle mode, on the other hand, is for terminal devices which areregistered to the network (EMM-REGISTERED), but not currently in activecommunication (ECM-IDLE). Thus, generally speaking, in RRC connectedmode a terminal device is connected to a radio network access node (e.g.an LTE base station) in the sense of being able to exchange user planedata with the radio network access node. Conversely, in RRC idle mode aterminal device is not connected to a radio network access node in thesense of not being able to communicate user plane data using the radionetwork access node. In idle mode the terminal device may still receivesome communications from base stations, for example reference signallingfor cell reselection purposes and other broadcast signalling. The RRCconnection setup procedure of going from RRC idle mode to RRC connectedmode may be referred to as connecting to a cell/base station. Inaddition to these idle and connected modes there are also proposals forother RRC modes, such as the so-called RRC_INACTIVE mode. A terminaldevice in RRC_INACTIVE mode is one which is not in an active RRCconnected mode with the radio access network (RAN), but is considered tobe RRC Connected from a CN (core network) point of view, so that datacan be sent without CN-level paging, but with paging performed insteadat the RAN level, to cause/trigger the terminal device to resume RRCconnection (enter an RRC connected mode). This approach has the benefitof being able to allow a terminal device to enter a more power efficientstate, while reducing the signalling between the CN and the RAN. Theoverall procedure allows RAN to take over responsibility for paging theterminal device, effectively hiding the RRC state transitions andmobility from the CN, and the CN therefore may directly send data as ifthe terminal device was still connected and in the same cell.

For a terminal device in RRC idle mode the core network is aware thatthe terminal device is present within the network, but the RAN part(comprising radio network infrastructure equipment such as the basestations 101 of FIG. 1 and/or the combined TRPs/CUs of FIG. 2) is not.The core network is aware of the location of idle mode terminal devicesat a paging tracking area level but not at the level of individualtransceiver entities. The core network will generally assume a terminaldevice is located within the tracking area(s) associated with atransceiver entity most recently used for communicating with theterminal device, unless the terminal device has since provided aspecific tracking area update (TAU) to the network. (As is conventional,idle mode terminal devices are typically required to send a TAU whenthey detect they have entered a different tracking area to allow thecore network to keep track of their location.) Because the core networktracks terminal devices at a tracking area level, it is generally notpossible for the network infrastructure to know which specifictransceiver entities (radio network node) to use when seeking toinitiate contact with a terminal device in idle mode. Consequently whena core network is required to connect to an idle mode terminal device apaging procedure is used.

In a typical currently deployed network, terminal devices which are notconnected to the network (i.e. not in RRC_CONNECTED mode) monitor forpaging messages periodically. For terminal devices operating in adiscontinuous reception (DRX) mode this occurs when they wake-up fortheir DRX awake time. Paging signals for a specific terminal device aretransmitted in defined frames (Paging Frames)/sub-frames (PagingOccasions) which for a given terminal device may be derived from theInternational Mobile Subscriber Identifier (IMSI) of the terminaldevice, as well as paging related DRX parameters established in systeminformation transmitted within the network.

In a conventional system, a terminal device thus receives and checks thecontents of specific sub-frames (paging occasions) in specific frames(paging frames) to look for paging signalling. For example, inaccordance with the procedures set out in 3GPP TS 36.304 version 14.2.0Release 14 [6], a Paging Frame (PF) is a downlink radio frame which maycontain one or more Paging Occasion(s) (PO), where a Paging Occasion isa sub-frame where there may be P-RNTI transmitted on PDCCH (orequivalent depending channel on implementation, e.g. MPDCCH or forNB-IoT on NPDCCH) addressing the paging message. Paging messages areconveyed on a physical downlink shared channel (PDSCH) on resourcesidentified from an allocation message addressed to a paging radionetwork temporary identifier (P-RNTI) and conveyed on a physicaldownlink control channel (PDCCH). P-RNTI is a common identifier for allterminal devices (e.g. set at FFFE in hexa-decimal for the standarddefined by 3GPP TS 36.321 version 13.5.0 Release 13 [7]). All terminaldevices check whether PDCCH at specific PFs/POs configured for their useinclude P-RNTI or not. If there is a PDSCH allocation addressed toP-RNTI in the relevant subframe, the terminal device proceeds to seek toreceive and decode the paging messages transmitted on the allocatedresources on PDSCH. The terminal device then checks the list of IDscontained in the paging record list in the received paging message, todetermine whether the list contains an ID corresponding to itself (forexample P-TMSI or IMSI), and if so initiates a paging response.

Although the above description has summarised an example existing LTEpaging procedure, it is expected that broadly similar principles may beadopted for future wireless telecommunications networks based on newerradio access technologies (RATs), such as 5G networks. Theabove-description of a paging procedure has referred to specific channelnames which are commonly used in LTE, such as PDCCH and PDSCH, and thisterminology will be used throughout this description for convenience, itbeing appreciated that in certain implementations different channelnames may be more common. For example in the context of a wirelesstelecommunications system having dedicated channels for communicatingwith certain types of terminal device, for example MTC devices, it maybe expected the corresponding channel names may be modified. Forexample, a physical downlink control channel dedicated for MTC devicesmay be referred to as MPDCCH and a corresponding physical downlinkshared channel for MTC devices may be referred to as MPDSCH.

In proposed approaches for eNB-IoT and feMTC in accordance with 3GPPrelease 14 a terminal device in DRX in idle mode decodes PDCCH (orequivalent downlink control channel for the specific implementation athand) to identify if there are resources scheduled on PDSCH (orequivalent downlink shared channel for the specific implementation athand) for a paging message during paging occasions in which the terminaldevice might receive a paging message.

FIG. 3 schematically represents a timeline of a paging occasion for aterminal device operating in a wireless telecommunications system. Inthe example shown in FIG. 3, one paging occasion is shown and extendsfrom time t1 to t2. Paging occasions for a terminal device willtypically occur according to a regular repeating schedule having regardto the terminal device's currently configured DRX cycle. Differentterminal devices may have different DRX cycle lengths, and so havedifferent times between paging occasions. For a terminal device having arelatively long DRX cycle/time between paging occasions, it is possiblethe terminal device will to some extent lose synchronisation with theradio network infrastructure equipment of the telecommunications systembetween paging occasions. Thus it may be helpful for a terminal devicesto wake-up in advance of a paging occasion to allow it to synchronise tothe wireless telecommunications system prior to the paging occasion. Anexample of this is schematically shown in FIG. 3 in which the terminaldevice wakes up at time t0 so that it can synchronise with the wirelesstelecommunication system in the period between times t0 and t1 so thatit is able to monitor/detect PDCCH during the configured paging occasionbetween t1 and t2. In this regard, the process of synchronisation mightin some cases only require fine adjustments to frequency and/or timingtracking loops based on detection of CRS (cell-specific referencesymbols), e.g. when DRX cycles (times between paging occasions) arerelatively short, or a more significant degree synchronisation may beneeded, for example complete re-synchronisation by detecting PSS/SSS(primary synchronisation signals/secondary synchronisation signals) aswell as using CRS, e.g. when DRX cycles (times between paging occasions)are relatively long (such that the frequency and timing of the terminaldevice may become significantly offset relative to that of the radionetwork infrastructure).

Once the terminal device has re-synchronised to the network, it willmonitor PDCCH to determine if there is a paging message, and if so willgo on to decode the PDSCH carrying the paging message in the usual way.If there is no paging message for the terminal device, the terminaldevice will go back to sleep (low power mode) until the next pagingoccasion. For certain types of terminal device, such as MTC devices, itmay be expected paging will occur relatively rarely (e.g. once per dayfor a smart utility meter), and so in many cases the terminal device maywake-up and synchronise to the network to monitor PDCCH by blinddecoding for a paging message when in fact there is no paging messagefor the terminal device. This represents an undesirable “waste” ofresources, for example battery power, for the terminal device.

Proposed approaches for eNB-IoT and feMTC in accordance with 3GPPrelease 15 share several common objectives, and one of these objectivesis to reduce power consumption associated with monitoring for pagingmassages. One proposal for this is to introduce what is referred to as awake-up signal (WUS) (e.g. of the type described in C. Hambeck, et al.,“A 2.4 μW Wake-up Receiver for wireless sensor nodes with −71 dBmsensitivity”, in IEEE Proceeding International Symposium of Circuits andSystems (ISCAS), 2011, pp. 534-537 [8]). The proposed WUS is carried ona new physical channel and is intended to allow terminal devices todetermine whether or not they need to actually decode PDCCH in anupcoming paging occasion. That is to say, whereas in accordance withpreviously proposed techniques a terminal device decodes PDCCH duringevery paging occasion to determine if there is a paging message, and ifso decodes PDSCH to determine if the paging message is addressed to theterminal device, the WUS is instead intended to indicate to the terminaldevice whether or not the next paging occasion contains a paging messagethat the terminal device should decode. A WUS is transmitted at apre-determined/derivable time in advance of a scheduled paging occasionsuch that a terminal device knows when to seek to receive a WUS and maycontain relatively little information so that it can be decoded quickly(as compared to the blind decoding needed for PDCCH). For example, insome implementations the WUS may include a one-bit indication of whetheror not there will be a paging message transmitted in the upcoming pagingoccasion. In some implementations the indication provided by the WUS maybe based on whether or not the WUS signalling is present.

If the WUS indicates the upcoming paging occasion does include a pagingmessage, any terminal devices for which that paging occasion applies mayproceed to decode the paging message as normal to determine if thepaging message is addressed to it. If the WUS indicates the upcomingpaging occasion does not include any paging message, any terminal devicefor which that paging occasion applies can determine from this that itdoes not need to monitor for a paging message during the upcoming pagingoccasion, and so can, for example, return to a low power mode. In someimplementations the WUS may include an identifier for a terminal devicethat is going to be paged in the paging occasion. This identifier mayidentify an individual terminal device or may identify a group ofterminal devices. The WUS may include multiple identifiers for multipleterminal devices/groups. A terminal device which determines the WUS isassociated with an identifier that applies to it may proceed to decodethe paging message as normal. Conversely, a terminal device whichdetermines the WUS is not associated with an identifier that applies toit may determine from this that it does not need to monitor for a pagingmessage during the upcoming paging occasion and can, for example, returnto a low power mode. The WUS may also be encoded with a format thatenables low power decoding (e.g. the WUS may be a narrow bandwidthsignal that can be decoded with low power using a low sampling ratereceiver), and furthermore may be transmitted with a format that allowsreliable decoding even with relatively poor synchronisation.

FIG. 4 schematically represents a timeline for a paging occasion for aterminal device operating in a wireless telecommunications systememploying a WUS as proposed in association with 3GPP Release 15. In theexample shown in FIG. 4, a paging occasion extends from time u2 to u3.As is conventional, the paging occasions will typically occur accordingto a regular repeating schedule having regard to the terminal device'scurrently configured DRX cycle.

As schematically indicated in FIG. 4, a WUS is transmitted at apredetermined/derivable time u1 in advance of the paging occasion toindicate there is a PDCCH paging message transmission for a terminaldevice indicated by an identifier associated with the WUS, which mayidentify an individual terminal device or a group of terminal devices.If the paging occasion is not scheduled to include a PDCCH pagingmessage transmission for a terminal device, then a WUS identifying thatterminal device is not sent. Thus a terminal device may be configured toseek to detect a WUS associated with an identifier for the terminaldevice in advance of an upcoming paging occasion. If the terminal devicedetects a WUS associated with an identifier for itself, the terminaldevice can proceed to fine tune its frequency and timing tracking loopsif required and blind detects for a PDCCH between times u2 and u3,followed by decoding of the PDSCH carrying the paging message betweentime u3 and u4 in the usual way. If, however, the terminal device failsto detect a WUS associated with an identifier for the terminal device,the terminal device may assume there is not going to be a paging messagefor the terminal device in the upcoming paging occasion, and so may goback to sleep (low power mode) and not decode PDCCH in the pagingoccasion. As noted above, in some other implementations, the WUS mightnot include any indication of any specific terminal device(s)/group(s),but may instead simply include an indication of whether or not anupcoming paging occasion includes any paging message, i.e. the WUS mayin effect be considered to apply to all terminal devices associated withthe relevant paging occasion (this will in effect restrict power savingsto paging occasions where no terminal devices are to be paged). Eitherway, by using WUS, a terminal device may be expected to consume lessenergy as it can help avoid unnecessary monitoring/blind decoding ofPDCCH (or equivalent depending on the specific implementation at hand).It will be appreciated that WUS can also be used in RRC_INACTIVE modeRRC_CONNECTED mode when DRX is used.

If a terminal device is configured for a long DRX cycle (i.e. arelatively long time between paging occasions), it is possible aterminal device will lose synchronisation with the radio access networkto an extent it is unable to decode WUS without first resynchronising tothe radio access network. An example of this approach is schematicallyshown in FIG. 4 whereby a terminal device configured for a relativelylong DRX cycle may be configured to wake-up at time u0 to allow time forit to synchronise to the radio access network before u1 so that it candetect any WUS signalling.

FIG. 5 schematically represents an example format for wake-up signals(WUS) that include a signature sequence (preamble) and an informationpart (info). The preamble part comprises signalling for terminal devicesto identify the signalling as a WUS and also, in some implementations,to use to achieve synchronisation with the network (i.e. with the radionetwork infrastructure equipment transmitting the WUS). The informationpart comprises an indication of one or more terminal devices to whichthe WUS applies, e.g. a terminal device identifier and/or an identifierfor a group of terminal devices. The terminal device/group identifier(s)may be network allocated identifiers (e.g. radio network temporaryidentifiers, RNTI) for the terminal device(s), or any other form ofsuitable identifier, e.g. based on an IMSI for a terminal device. Itwill be appreciated the format for the wake-up signalling may notconform to that shown in FIG. 5, but may in other implementations have adifferent format. For example, the wake-up signalling may have a formatin which the wake-up signalling comprises a preamble (signaturesequence) without a separate information part. Instead, the preamble mayitself contain an indication of the identity for the terminal device(s)for which the wake-up signalling indicates a paging message is to besubsequently transmitted, for example with specific WUS preambles(sequences/patterns) configured for specific terminal devices/groups ofterminal devices.

FIG. 6 schematically shows some aspects of a telecommunications system500 configured to support communications between a terminal device 508and network access nodes 504, 506 in accordance with certain embodimentsof the disclosure. Many aspects of the operation of thetelecommunications system/network 500 are known and understood and arenot described here in detail in the interest of brevity. Aspects of thearchitecture and operation of the telecommunications system 500 whichare not specifically described herein may be implemented in accordancewith any previously proposed techniques, for example according tocurrent 3GPP standards and other proposals for operating wirelesstelecommunications systems/networks. The network access nodes 504, 506may, for convenience, sometimes be referred to herein as base stations504, 506, it being understood this term is used for simplicity and isnot intended to imply any network access node should conform to anyspecific network architecture, but on the contrary, may correspond withany network infrastructure equipment/network access node that may beconfigured to provide functionality as described herein. In that senseit will appreciated the specific network architecture in whichembodiments of the disclosure may be implemented is not of primarysignificance to the principles described herein.

The telecommunications system 500 comprises a core network part (evolvedpacket core) 502 coupled to a radio network part. The radio network partcomprises the radio network access nodes 504, 506 and the terminaldevice 508. It will of course be appreciated that in practice the radionetwork part may comprise a more than two network access nodes servingmultiple terminal devices across various communication cells. However,only a two network access nodes and one terminal device are shown inFIG. 6 in the interests of simplicity.

As with a conventional mobile radio network, the terminal device 508 isarranged to communicate data to and from the network access nodes (basestations/transceiver stations) 504, 506. Typically the terminal devicewill be operable to connect to (i.e. be able to exchange user plane datawith) one network infrastructure element at a time, and so as theterminal device moves around the network it may move in and out ofcoverage of the different network access nodes comprising the network.The network access nodes 504, 506, are communicatively connected to aserving gateway, S-GW, (not shown) in the core network part which isarranged to perform routing and management of mobile communicationsservices to the terminal devices in the telecommunications system 500via the network access nodes 504, 506. In order to maintain mobilitymanagement and connectivity, the core network part 502 also includes amobility management entity, MME, 520 which manages the enhanced packetservice, EPS, connections with terminal devices operating in thecommunications system based on subscriber information stored in a homesubscriber server, HSS. Other network components in the core network(also not shown for simplicity) include a policy charging and resourcefunction, PCRF, and a packet data network gateway, PDN-GW, whichprovides a connection from the core network part 502 to an externalpacket data network, for example the Internet. As noted above, theoperation of the various elements of the communications system 500 shownin FIG. 6 may be in accordance with known techniques apart from wheremodified to provide functionality in accordance with embodiments of thepresent disclosure as discussed herein.

The terminal device 508 is adapted to support operations in accordancewith embodiments of the present disclosure when communicating with thenetwork access nodes 504, 506. In this example the terminal device 508is assumed to be an MTC terminal device. The terminal device 508 may bea dedicated MTC terminal device, such as a wearable technology item, ormay be a generic terminal device, such as a smartphone terminal device,running an application that relies on MTC data exchange. Nonetheless, itwill be appreciated the principles disclosed herein may also be appliedfor other types of terminal device (i.e. devices which may not beconsidered MTC devices). The terminal device 508 comprises transceivercircuitry 508 a (which may also be referred to as atransceiver/transceiver unit) for transmission and reception of wirelesssignals and processor circuitry 508 b (which may also be referred to asa processor/processor unit) configured to control the terminal device508. The processor circuitry 508 b may comprise varioussub-units/sub-circuits for providing desired functionality as explainedfurther herein. These sub-units may be implemented as discrete hardwareelements or as appropriately configured functions of the processorcircuitry. Thus the processor circuitry 508 b may comprise circuitrywhich is suitably configured/programmed to provide the desiredfunctionality described herein using conventionalprogramming/configuration techniques for equipment in wirelesstelecommunications systems. The transceiver circuitry 508 a and theprocessor circuitry 508 b are schematically shown in FIG. 6 as separateelements for ease of representation. However, it will be appreciatedthat the functionality of these circuitry elements can be provided invarious different ways, for example using one or more suitablyprogrammed programmable computer(s), or one or more suitably configuredapplication-specific integrated circuit(s)/circuitry/chip(s)/chipset(s).It will be appreciated the terminal device 508 will in general comprisevarious other elements associated with its operating functionality, forexample a power source, user interface, and so forth, but these are notshown in FIG. 6 in the interests of simplicity.

The network access nodes 504, 506 each comprises transceiver circuitry504 a, 506 a (which may also be referred to as a transceiver/transceiverunit) for transmission and reception of wireless signals and processorcircuitry 504 b, 506 b (which may also be referred to as aprocessor/processor unit) configured to control the respective networkaccess nodes 504, 506 to operate in accordance with embodiments of thepresent disclosure as described herein. Thus, the processor circuitry504 b, 506 b for each network access node 504, 506 may comprisecircuitry which is suitably configured/programmed to provide the desiredfunctionality described herein using conventionalprogramming/configuration techniques for equipment in wirelesstelecommunications systems. For each network access nodes 504, 506 thetransceiver circuitry 504 a, 506 a and the processor circuitry 504 b,506 b are schematically shown in FIG. 6 as separate elements for ease ofrepresentation. However, it will be appreciated that the functionalityof these circuitry elements can be provided in various different ways,for example using one or more suitably programmed programmablecomputer(s), or one or more suitably configured application-specificintegrated circuit(s)/circuitry/chip(s)/chipset(s). It will beappreciated that each of the network access nodes 504, 506 will ingeneral comprise various other elements associated with its operatingfunctionality, such as a scheduler. For example, although not shown inFIG. 6 for simplicity, the processor circuitry 504 b may comprisescheduling circuitry, that is to say the processor circuitry 504 b maybe configured/programmed to provide the scheduling function for thenetwork access node.

The network access nodes 504, 506 are operable to communicate with theterminal device 508 (when in coverage) over respective radiocommunication links 512, 514. The network access nodes 504, 506 areoperable to communicate with each other to share information through acommunications link 210 between them. In some network architectures thenetwork nodes may communicate directly with one another, asschematically represented in FIG. 6, while in other networkarchitectures they may communicate with one another indirectly, e.g. viathe core network part 502.

As noted above, a WUS comprises a predefined signature sequence/preamblewhich a terminal device is able to readily detect, e.g., when in a powersaving mode (PSM). The specific signature sequence/preamble used in agiven implementation may be referred to as a WUSsequence/preamble/pattern, or more generally as a WUS format, for theWUS signalling. A wireless network communications system may beconfigured so that different radio access nodes are associated withdifferent WUS formats, for example to help avoid neighbouring cellinterference. More generally, different radio access nodes may beassociated with different WUS configurations, for example also havingdifferent periodicities and relative offsets in terms of the timings ofWUS signals and associated paging occasions as well as different WUSsignalling formats (WUS patterns). Thus, a network access node to whicha terminal device is attached may provide the terminal device withcell-specific WUS configuration information so that when the terminaldevice enters the power saving mode, it has the information necessary toallow it to seek to detect WUS signalling from the network access node.The inventors have recognised a potential issue with this can arise forterminal devices which have a degree of mobility within thetelecommunications system such that they may move out of the coveragearea associated with a first network access node to the coverage areaassociated with a second network access node while in the power savingmode. This may occur because the terminal device is physically mobile,or because the terminal device is physically stationary, but nonethelessmoves between cells due to changing cell conditions (e.g. so-calledping-ponging at a cell edge). It is expected a terminal device will notmake measurements in the power saving mode (beyond seeking to detect WUSsignalling), and so the terminal device will not be aware it has movedfrom the coverage of the first network access node to the coverage ofthe second network access node. Consequently, the terminal device willcontinue to seek WUS signalling in accordance with the configurationinformation settings received from the first network access node. Thismeans the terminal device becomes uncontactable because it cannotreceive WUS signalling from the first network access node because ofcoverage issues, and it cannot receive WUS signalling from the secondnetwork access node because it does not have the appropriate WUSconfiguration (i.e. it is searching for the wrong WUS format,potentially also at the wrong times). One way to overcome this problemwould be to only use WUS procedures for static/relatively immobileterminal devices. However, the inventors have recognised there can stillbe useful power savings available to terminal devices that are mobile(subject to changing cell coverage) if they could also make use of WUSprocedures.

Thus, certain embodiments of the disclosure provide for configuring aterminal device in a wireless telecommunications system with multipleWUS configurations at the same time, e.g. a different WUS configurationfor at least some of the plurality of network access nodes. Thus theterminal device may establish first wake-up signalling configurationinformation comprising an indication of a first wake-up signallingformat for a first network access node and second wake-up signallingconfiguration information comprising an indication of a second wake-upsignalling format for a second network access node. This may bestablished, for example, from information received from the firstnetwork access node, e.g. in SIB (system information broadcast)signalling or RRC (radio resource control) signalling. Havingestablished this information the terminal device is thus able to monitorfor cell specific WUS signalling transmitted by either one of the firstand second network access nodes and respond accordingly (e.g. seek todecode a subsequent paging message associated with the WUS signalling).Thus, if the terminal device is initially configured for WUS operationwhen attached to the first network access node, but subsequently movesfrom the coverage area of the first network access node to the coveragearea of the second different network access node, the terminal devicecan still detect and react to WUS signalling. In terms of detecting andreacting to WUS signalling, it will be appreciated certain embodimentsof the disclosure represent a development of previously proposed WUSschemes, and aspects and features of approaches in accordance withembodiments of the disclosure which correspond with aspects and featuresof existing WUS proposals, for example in terms of determining when WUSsignalling is transmitted, specific WUS formats to use, WUS signallingdetection techniques and so on, may be based on existing proposals.

Thus in accordance with some embodiments of the disclosure a terminaldevice in a wireless telecommunications system that uses cell-specificWUS signalling may still be paged using WUS even if it moves from thecoverage of one cell to another. It will be appreciated the terminaldevice may establish WUS configuration information for more than twonetwork access nodes so that it can be paged using WUS in more than twocells. In principle a terminal device could establish WUS configurationinformation for every network access node operating in the network sothat it is contactable by WUS wherever it is located within the network.However, in practice, this may not be considered an optimum approachbecause of the large amount of decoding attempts and time that might beneeded for the terminal device to detect WUS signalling. Consequently,the terminal device may be configured with WUS configuration informationfor only a restricted number of radio network access nodes, for examplefor two neighbouring radio access nodes if the terminal device isphysically stationary in the vicinity of a boundary between the twoneighbouring radio access nodes, but prone to ping-ponging between them(moving between coverage areas due to changing radio conditions). Moregenerally, a compromise may be made between the ability to page theterminal device using WUS over a larger area and the amount ofcomplexity involved in managing and seeking to decode multiple WUSconfigurations. For example a terminal device may be configured with WUSsettings for the network access nodes in a tracking area containing thenetwork access node to which it was attached when it established themultiple WUS configurations. In situations in which a terminal devicemoves to a location covered by a radio access node for which it does nothave a WUS configuration, a separate recovery mechanism may be used. Forexample, a terminal device may be configured to perform a cellselection/reselection procedure if it determines that it has not beenpaged for more than a threshold amount of time, i.e. what might beconsidered a validity period for the WUS configuration information forat least one of the radio access nodes.

FIG. 7 is a ladder diagram schematically representing some operatingaspects of the wireless telecommunications system 500 discussed abovewith reference to FIG. 6 in accordance with certain embodiments of thedisclosure. In particular, the diagram represents some operations andsignalling exchange associated with the terminal device 508, the networkaccess node 504, which for convenience may be referred to here as afirst network access node 504 (eNB1), the network access node 506, whichfor convenience may be referred to here as a second network access node506 (eNB2), and the MME 520 in the core network 502 in accordance withcertain embodiments of the disclosure.

The processing of FIG. 7 starts in step S1 in which the first networkaccess node and the second network access node exchange WUSconfiguration information such that the first network access node ismade aware of the WUS configuration information for the second networkaccess node, and the second network access node is made aware of the WUSconfiguration information for the first network access node. The WUSconfiguration information for the first network access node may beconveniently referred to as first WUS configuration information and theWUS configuration information for the second network access node may beconveniently referred to as second WUS configuration information. TheWUS configuration information may be exchanged between the respectivenetwork access nodes using conventional techniques for exchanginginformation between network access nodes, e.g. across an X2 interface,for example during an X2 setup procedure if the WUS configurationinformation is relatively static.

As indicated in Step S2, for the scenario represented in FIG. 7 theterminal device 508 is initially in RRC_IDLE mode and configured for adiscontinuous reception (DRX) mode of operation with the network accessnode 504 in a manner that uses wake-up signalling (i.e. providing theterminal device with an indication of whether an upcoming pagingoccasion will include a paging message that may be for the terminaldevice). This may be generally in accordance with previously proposedtechniques, but modified in accordance with embodiments of thedisclosure as discussed further herein.

As schematically indicated in step S3, the first network access nodetransmits WUS configuration information and this is received by theterminal device 508. The WUS configuration information comprises WUSconfiguration information for the first network access node and WUSconfiguration information for the second network access node (which thefirst network access node established from signalling received from thesecond network access node in step S1). In this example the WUSconfiguration information is transmitted in a system informationbroadcast, SIB, message transmitted by the first network access node.Thus, in step S2 the terminal device 508 establishes wake-up signalling(WUS) configuration information for both the first network access node504 covering the current location for the terminal device 508 and thesecond network access node 506. In accordance with certain embodimentsof the disclosure the wake-up signalling configuration information foreach network access node comprises an indication of a respective WUSformat (signature sequence) for paging the terminal device via thecorresponding network access node.

As indicated in step S4, after receiving the first and second WUSconfiguration information in step S3, the terminal device 508 may entera power saving mode in which it monitors for signalling transmitted bythe first network access node that matches the first wake-up signallingformat and for signalling transmitted by the first network access nodethat matches the first wake-up signalling format (either at the sametime or in a time multiplexed manner as discussed further herein).

For the example implementation represented in FIG. 7, it is assumedsteps S5 to S9 are performed while the terminal device remains in thecoverage area of the first network access node.

In step S5 the MME determines a need to page the terminal device. Thereason why the terminal device is to be paged is not significant to theprinciples described herein. For example, there may be data that needsto be transmitted to the terminal device, or there may be a desire totrigger the terminal device to transmit data to the network.

In steps S6 and S7 the MME 520 sends respective paging request messagesto the first network access node 504 and the second network access node506. These paging request messages may be conventional. In that regardit will be appreciated the overall paging strategy, for example in termsof which network access nodes are requested to page the terminal device,when they should do so, and how many attempts they should make, in anygiven scenario is not significant to the principles described herein.

In step S8 the first network access node 504 pages the terminal device508 using the WUS procedure. That is to say the first network accessnode 504 transmits a WUS in accordance with the first WUS format andtimings defined in the first WUS configuration information transmittedto the terminal device in step S3, and follows this with a pagingmessage in the relevant paging occasion. This aspect of the processingof FIG. 7 may be performed in accordance with previously proposedtechniques for paging using WUS.

As indicated in step S9 in this scenario it is assumed the pagingstrategy is such that the second network access node 506 also seeks topage the terminal device 508 using the WUS procedure in parallel withthe first network access node in step S8. That is to say the secondnetwork access node 506 transmits a WUS in accordance with the secondWUS format and timings defined in the second WUS configurationinformation transmitted to the terminal device in step S3, and followsthis with a paging message in the relevant paging occasion. However,although the terminal device 508 has been provided with the relevant WUSconfiguration information to receive WUS signalling from the secondnetwork access node, the paging in step S9 fails because the terminaldevice is in this example scenario assumed to be not in coverage of thesecond network access node 506.

As schematically indicated in step S10, and in response to havingsuccessfully received the paging message transmitted using WUS by thefirst network access node in step S8, the terminal device responds tothe paging message in the conventional way, and after any furthersignalling associated with the cause for the paging is completed, theterminal device may return to the power saving mode in which itcontinues to monitor for WUS signalling for any further paging events.When the terminal device returns to RRC_IDLE having enteredRRC_CONNECTED mode in response to the paging message, the terminaldevice may, for example, continue to use the existing WUS configurationinformation from step S3, or use new/updated WUS configurationinformation. New/updated WUS configuration information may, for example,be received in an RRC message, e.g. an RRC connection release messagewhen in RRC_CONNECTED mode in response to the paging message, or in acell selection/reselection procedure after returning to RRC_IDLE mode.

Thus, the processing of steps S5 to S10 represents the successfulcompletion of a paging event for the terminal device 508 using WUS viathe first network access node 504, i.e., without the terminal devicemoving out of coverage of the network access node to which it mostrecently connected.

However, in the example processing represented in FIG. 7, it is assumedin step S11 the terminal device moves out of the coverage area of thefirst network access node 504 and into the coverage area of the secondnetwork access node 506. This may occur due to physical movement of theterminal device or due to changing radio conditions impacting thecoverage areas of the respective network access nodes. Because theterminal device is operating in a power saving mode in which it does notmake cell measurements, the terminal device does not know it has movedout of coverage of the first network access node and into coverage ofthe second network access node, and consequently nor does the MME or anyother network infrastructure element know this.

In step S12 the MME determines a need to page the terminal device again.The reason why the terminal device is to be paged is again notsignificant to the principles described herein.

In the same way as discussed above for steps S6 and S7, in steps S13 andS14 the MME 520 sends respective paging request messages to the firstnetwork access node 504 and the second network access node 506. Thesepaging request messages may again be conventional.

In step S15 the first network access node 504 attempts to page theterminal device 508 using the WUS procedure. That is to say the firstnetwork access node 504 transmits a WUS in accordance with the first WUSformat and timings defined in the first WUS configuration informationtransmitted to the terminal device in step S3, and follows this with apaging message in the relevant paging occasion. However, this pagingattempt by the first network access node in step S15 fails because theterminal device is in this example scenario assumed to be not incoverage of the first network access node 506 having moved to thecoverage area of the second network access node in step S11.

As indicated in step S16, and as noted above, in this exampleimplementation the paging strategy is such that the second networkaccess node 506 also seeks to page the terminal device 508 using the WUSprocedure in parallel with the first network access node's attempt instep S15. Thus in step S16 the second network access node 506 transmitsa WUS in accordance with the second WUS format and timings defined inthe second WUS configuration information transmitted to the terminaldevice in step S3, and follows this with a paging message in therelevant paging occasion. Because the terminal device 508 has beenprovided with the relevant WUS configuration information to receive WUSsignalling from the second network access node (in step S3), and becauseit has moved into coverage of the second network access node (in stepS11), the terminal device is able to successfully detect the WUSsignalling from the second network access node and receive theassociated paging message in the relevant paging occasion in step S16.

In step S17 the terminal device responds to the paging message receivedin step S16 in the conventional way, and after any further signallingassociated with the cause for the paging is completed, the terminaldevice may returns to the power saving mode in which it continues tomonitor for WUS signalling. As part of step S17 the terminal device maybe configured to decode system information broadcast, SIB, signallingtransmitted by the second network access node to facilitate the responseto the paging message, for example in the even the terminal device needsto acquire cell-specific information associated with the second networkaccess node to respond to the paging message using the second networkaccess node. When the terminal device returns to RRC_IDLE having enteredRRC_CONNECTED mode in response to the paging message, the terminaldevice may, for example, continue to use the existing WUS configurationinformation from step S3, or use new/updated WUS configurationinformation. New/updated WUS configuration information may, for example,be received from the second network access node in an RRC message, e.g.an RRC connection release message when in RRC_CONNECTED mode in responseto the paging message, or in a cell selection/reselection procedureafter returning to RRC_IDLE mode.

Thus, the processing of steps S12 to S17 represents the successfulcompletion of a paging event for the terminal device using WUS, despitethe terminal device having moved out of coverage of the network accessnode which configured it to receive WUS signalling.

Thus, the approach set out above of configuring a terminal device withmultiple WUS configurations allows the terminal device to recover from asituation in which it would otherwise have become non-contactable.

It will be appreciated the processing represented in FIG. 7 sets outonly some of the steps involved in the procedure, and for simplicity andease of representation, some steps performed in accordance with thisexample implementation are not shown in FIG. 7 or amalgamated into fewersteps.

Furthermore, it will further be appreciated there are variousmodifications that may be made to the processes described herein inaccordance with other example implementations.

For example, whereas the processing discussed above with reference toFIG. 7 concerns a terminal device in RRC_IDLE mode (as indicated in stepS2), the same approach may be used for a terminal device starting inRRC_INACTIVE mode.

Furthermore, whereas the WUS configuration information from the firstnetwork access node is provided to the terminal device in a systeminformation broadcast, SIB, message in step S3 in FIG. 7, the WUSconfiguration information may also be provided to the terminal device inother ways, for example through radio resource control, RRC, signallingat an earlier time when the terminal device was in RRC_CONNECTED mode.

Furthermore, whereas the example of FIG. 7 shows two network accessnodes sharing aspects of their WUS configuration information, forexample for a terminal device that frequently moves between them, thesame approach may be used with more network access nodes sharing aspectsof their WUS configuration information, for example for a terminaldevice that frequently moves between more than two network access nodes,or among a defined group of network access nodes, for example, those ina tracking area.

Whereas in the example of FIG. 7 the first and second network accessnodes share WUS configuration information in step S1 so that the firstnetwork access node can provide the terminal device with the WUSconfiguration information for the second network access node in step S3,in other examples there are other ways in which the terminal device canobtain the relevant configuration information, for example as shown inFIG. 8.

FIG. 8 is a ladder diagram schematically representing some operatingaspects of the wireless telecommunications system 500 as discussed abovewith reference to FIG. 6 in accordance with certain other embodiments ofthe disclosure. Various aspects of FIG. 8 are similar to, and will beunderstood from, corresponding aspects of FIG. 7. However, FIG. 8represents a modified approach to that represented in FIG. 7 in whichthe terminal device establishes WUS configuration information formultiple network access nodes in a different way.

In accordance with the approach generally set out in FIG. 8 an MME maybe configured to establish an identifier for each of different subsetsof terminal devices registered with the MME and which may be paged usingWUS in accordance with the principles described herein. The manner inwhich the terminal devices are divided into groups, the number ofgroups, and the number of terminal devices within each group, are notsignificant to the principles described herein. For example, the MME maysimply define ten groups with terminal devices placed into groupsaccording to the last digit of a terminal device unique identifier, forexample an IMSI. However, in other approaches the terminal devices maybe grouped having regard to other characteristics, for example so thatterminal devices which may be expected to be paged at the same time, forexample smart meters belonging to a particular utility company, aregrouped together. Each group may thus be associated with what may bereferred to as a WUS Global ID, which in practice may be a simpleindex/group number. In principle each group may comprise a singleterminal device, but in practice the management of the scheme may besimplified by grouping multiple terminal devices together (e.g. toreduce the number of different WUS Global IDs and WUS signaturesequences required).

The processing of FIG. 8 starts in step T1 with the terminal device 508in RRC_IDLE and configured for a discontinuous reception (DRX) mode ofoperation with the network access node 504 in a manner that uses wake-upsignalling. This may be generally in accordance with previously proposedtechniques, but modified in accordance with embodiments of thedisclosure as discussed further herein.

In step T2 the MME transmits signalling to the terminal device toindicate the WUS Global ID for the group the MME has allocated for theterminal device. In this example, with the terminal device in RRC_IDLE,this information is provided via the first network access node throughSIB signalling, but the indication of the relevant WUS Global IDallocated by the MME to the terminal device may equally be transmittedin any of a number of different ways. For example the WUS Global IDinformation may also be provided to the terminal device through radioresource control, RRC, signalling from an earlier time when the terminaldevice was in RRC_CONNECTED mode.

In step T3 the terminal device derives cell-specific first and secondWUS signalling formats for the first network access node (servingnetwork access node) and the second network access node (neighbournetwork access node) respectively. The cell-specific WUS signallingformats (and other relevant WUS configuration information) may bederived from a predefined function having the WUS Global ID for theterminal device as one input and the cell ID for the relevant networkaccess node as a second input, for example based on a predefined look-uptable. The terminal device knows its WUS Global ID from the signallingreceived in step T2, and can determine the cell IDs for it serving celland neighbouring cells in the usual way (e.g. from a Neighbour Cell Listtransmitted by the first network access node to which the terminaldevice is initially attached). Thus the terminal device can determinefrom this information, and the predefined mapping function/look-up table(e.g. predefined by standard), what WUS signalling format to receivefrom the various network access nodes.

As indicated in step T4, after deriving the first and second WUSconfiguration information in step T3, the terminal device 508 may entera power saving mode in which it monitors for signalling transmitted bythe first network access node that matches the first wake-up signallingformat and for signalling transmitted by the first network access nodethat matches the first wake-up signalling format (either at the sametime or in a time multiplexed manner as discussed further herein).

For the example implementation represented in FIG. 7, it is assumedsteps T5 to T12 are performed while the terminal device remains in thecoverage area of the first network access node.

In step T5 the MME determines a need to page the terminal device. Thereason why the terminal device is to be paged is not significant to theprinciples described herein. For example, there may be data that needsto be transmitted to the terminal device, or there may be a desire totrigger the terminal device to transmit data to the network.

In steps T6 and T7 the MME 520 sends respective paging request messagesto the first network access node 504 and the second network access node506. These paging request messages may be based on conventional pagingrequest messages, but in accordance with embodiments of the disclosureare modified to include an indicator of the WUS Global ID relevant forthe terminal device that the MME wishes to page.

In steps T8 and T9 the respective network access nodes derive their owncell-specific WUS signalling formats using the same predefined mappingfunction/look-up table as the terminal device uses in step T3, which maybe standardised in the network, or otherwise determined and shared amongthe relevant elements of the network, e.g., with coordination by theMME. The respective network access nodes know the relevant WUS Global IDto use from the paging request messages received in steps T6 and T7, andknow their own cell IDs, so they can derive the relevant WUS signallingformat they should each use. As already noted above, it will beappreciated the overall paging strategy, for example in terms of whichnetwork access nodes are requested to page the terminal device, whenthey should do so, and how many attempts they should make, in any givenscenario is not significant to the principles described herein.

In step T10 the first network access node 504 pages the terminal device508 using the WUS procedure. That is to say the first network accessnode 504 transmits a WUS in accordance with the first WUS format itderived in step T8, and follows this with a paging message in therelevant paging occasion. This aspect of the processing of FIG. 8 may beperformed in accordance with previously proposed techniques for pagingusing WUS. That is to say, what is significant for this embodiment isthe different manner in which the network access node derives thespecific WUS signalling format to use from its own cell ID and theidentification information received from the MME in association with thepaging message, and not the specific manner in which the WUS signallingis transmitted.

As indicated in step T11 in this scenario it is assumed the pagingstrategy is such that the second network access node 506 also seeks topage the terminal device 508 using the WUS procedure in parallel withthe first network access node. That is to say the second network accessnode 506 transmits a WUS in accordance with the second WUS format itderived in step T9, and follows this with a paging message in therelevant paging occasion. This aspect of the processing of FIG. 8 mayagain be performed in accordance with previously proposed techniques forpaging using WUS.

As noted above, for the example scenario represented in FIG. 8, it isassumed the terminal device remains in coverage of the first networkaccess node, and as such it detects the WUS signalling from the firstnetwork access node in step T10 and subsequent paging message. Thus, asindicated in FIG. 8, the attempt to page the terminal device in step T11fails because the terminal device is not in coverage of the secondnetwork access node. However, it will be appreciated that if theterminal device has moved from the coverage area of the first networkaccess node to the second network access node, while it would notreceive the paging message in step T10, it would instead receive thepaging message in step T11. That is to say, the terminal device wouldremain pageable using WUS regardless of whether it moves between cellsbecause it supports multiple WUS configurations as discussed above.

As schematically indicated in step T12, and in response to havingsuccessfully received the paging message transmitted using WUS by thefirst network access node in step T10, the terminal device responds tothe paging message in the conventional way, and after any furthersignalling associated with the cause for the paging is completed, theterminal device may return to the power saving mode in which itcontinues to monitor for WUS signalling for any further paging events.

Thus, to summarise some aspects of certain embodiments of thedisclosure, a UE may be configured with multiple WUS configurations, forexample configurations relating to a plurality of neighbouring cells.The WUS configuration for the neighbouring cells may, for example,include an indication of a WUS sequence, radio resources (in time andfrequency) used for WUS signalling, WUS signalling location (e.g. anindication of a narrowband within a broader network frequency range anda periodicity for the WUS signalling), a WUS signalling repetitionnumber (e.g. if different cells support different amounts of coverageextension), and potentially a WUS validity timer (i.e. a duration forwhich the associated WUS configuration is considered to remain valid,and after which the UE should seek new/updated WUS configurationinformation, for example by performing a cell selection/reselectionprocedure).

Thus, in addition to a serving cell's specific WUS settings, the UE canalso be configured with one or more neighbour cells' WUS settings. Asdescribed herein, the network may not be aware when a UE has moved cellsand hence providing the UE with the WUS configuration for a neighbouringcell can help enable the UE to detect the WUS used by a cell without theneed to read the SIB of the cell and be reconfigured, which can in somecases consume a relatively large amount of battery power. This approachcan thus help a UE to save power (by not reading the SIB in the newcell). In some implementations a UE may check (i.e. monitor for/seeks todetect) more than one WUS sequence before each paging occasion, and soit can in some cases be helpful to restrict the number of simultaneousWUS sequences the terminal device is configured to seek to blind decodefor a given paging occasion to reduce UE complexity.

In some cases where there may be a particular desire to further reduceUE complexity, for example by adopting approaches in which the terminaldevice does not need to blind decode for multiple (or at least more thana threshold number of) WUS sequences/formats for at least some pagingoccasions. In one example this may be achieved by having multiplenetwork access nodes adopt the same WUS configuration, so that theterminal device can be configured for, and attempt to blind decode, justa single WUS signalling format/sequence. In this case an MME entity maybe configured to indicate the WUS signalling format a network accessnode should use in association with a paging request message sent to thenetwork access node. In some examples this could be signalledexplicitly, which would require some modification of the MME, which maynot be desired from a network management perspective. Alternatively theindication of which WUS sequence to use for a paging message may beconveyed to the network access nodes implicitly. For example, it isknown for an MME to include a “recommended cells for paging” informationelement in a paging request message sent to network access nodesindicating the most recently visited cells by the UE in order. Therespective network access nodes may thus be configured to select a WUSformat to use based on which network access node is listed as mostrecently visited/connected to, for example. The mapping between networkaccess nodes and WUS formats may be statically defined in the network,or each network access nodes may select its own WUS format and sharethis among other radio access nodes that may need the information in adynamic way, e.g. using X2 signalling, for example other network accessnodes in its paging tracking area. In some examples the WUS signallingformat may allow a network access node to convey a degree of additionalinformation to the terminal device. For example, in addition tocomprising a predefined WUS pattern, the WUS signalling format may allowfor some additional data that may be selected by the network accessnode, for example in an appropriately configured preamble or aninformation part associated with a preamble. A network access node mayuse this to in effect provide the UE with an indication it has movedcell/network access node. That is to say, a neighbour cell may getinformation for the WUS configuration of a serving cell and transmit theserving cell WUS with an indication in the additional data of the WUSsignalling to indicate the WUS signalling is not coming from the initialserving radio access node (e.g. this may be network access nodeidentifier). The UE may be configured to react to this by performingcell reselection or otherwise reacquiring an updated WUS configurationfrom the new cell (i.e. the cell to which it has moved).

In another example to help reduce blind decoding requirements for a UE,the UE may be configured with at least two WUS configurations asdiscussed above, but may seek to blind decode in accordance with each ofthem for different paging occasions in a time multiplexed manner. Thatis say, the UE may seek to decode fewer, e.g. in some cases only one,WUS sequences per paging occasion than the total number of WUS sequencesfor which it has been configured.

For example, the UE may use (i.e. seek to decode) a first WUS sequenceassociated with a first WUS configuration for a first period, e.g.comprising N1 consecutive paging occasions, and if it fails to detectthe first WUS sequence in the first period (i.e. for N1 consecutive WUSoccasions, wherein a WUS occasion is a time at which WUS couldpotentially be transmitted), it will then use the second WUSconfiguration for a second period, e.g. comprising N2 consecutive pagingoccasions, and if it fails to detect the second WUS sequence in thesecond period (i.e. for N2 consecutive WUS occasions), it may then use athird WUS sequence associated with a third WUS configuration (if it hasone) for a third period, and so on. Thus the criterion for switchingfrom one WUS configuration to the next may be based on the amount oftime for which each WUS configuration is used without detecting WUSsignalling (e.g. values for N1 and N2). For example, the first WUSsequence may be cell specific (e.g. relating to the cell which providedthe UE with its configuration information), whilst a second WUS sequencemay be a group cell-specific WUS sequence (e.g. common to a group ofneighbour cells that share the same sequence or a TA area shares thesame sequence). The UE can thus start using the first WUS sequence, andupon failing to detect WUS signalling for N1 consecutives WUS occasions,it may switch to use the second WUS sequence. The second WUS sequencemay be associated with a larger periodicity (i.e. transmitted lessoften) than the first WUS sequence. Hence the UE would initially use afirst WUS sequence in its serving cell and when it has moved cell(without the UE realising it) during a power saving mode, the UE willfail to detect the first WUS sequence, but since the second WUS sequenceis transmitted by neighbouring cells, the UE will hence be able todetect it. The second WUS sequence may be always transmitted by theneighbouring cells or used only when the MME indicates it to the cellsdepending on the implementation at hand. When all WUS configurationsavailable to the UE have been attempted and failed to detect any WUS,the UE may, for example, perform reselection and reacquire WUSconfiguration in the new cell.

As noted above, in some implementations the WUS configurationinformation may include a validity timer/period for each WUS sequence.In some examples a UE with multiple WUS configurations might initiallyuse a first WUS configuration until its validity timer expires, afterwhich it may use a second WUS configuration and so on. That is thetermination criterion (which when met causes the UE to switch to thenext WUS) may be the validity timer of each WUS, with the validity timerfor one WUS sequence starting when the previous ones expires (i.e. withthe timers running in sequence rather than parallel). The durations forthe different validity timers can for example be configured based on thecoverage of the network access node(s) using the corresponding WUS. Forexample, if a first WUS configuration is used within a single cell, e.g.the serving cell for the UE when it last performed cell selection, itmay have a smaller validity timer (i.e. expires faster) and a second WUSconfiguration common to a group of cells that covers a larger area andtherefore may be configured with a larger validity timer (on the basisit may take the UE longer to move out of coverage of radio access nodesusing this WUS sequence). In some cases, when any, or a selected group,of the validity timers expire, the UE may perform cellreselection/connection to seek to obtain the latest WUS configurations.For example, if a UE is configured with four different WUSconfigurations, the UE might only perform cell reselection/connection toupdate its WUS configurations if the 2nd and 3rd WUS validity timersexpire, for example.

While some of the above examples have focused on approaches in which aUE might only attempt to blind decode for one WUS sequence at a time(e.g. per paging occasion) to reduce computational effort and associatedpower usage and circuitry complexity, it will be appreciated otherexamples may reduce complexity by having the UE blind decode for fewerthan its total number of WUS configurations per paging occasion, butmore than one. For example, a UE with five WUS configurations mayattempt to blind decode for two different WUS configurations at for eachpotential WUS occasion in a first time period, and after failing todecode WUS signalling in that period (e.g. after N1 attempts), the UEmay switch to attempting to blind decode for the remaining threedifferent WUS configurations at for each potential WUS occasion in asecond time period (i.e. the number of WUS sequences to attempt to blinddecode may be different in different time periods). It will beappreciated different criterion can be used to determine when to switchbetween seeking different WUS sequences. For example, a first group ofone or more WUS sequences may be attempted for a given number of WUSoccasions, after which a second group of one or more WUS sequences maybe attempted until a validity timer (either defined for the group as awhole or individually for each configuration in the group) expires.

In some other examples WUS signalling may indicate another one or moreWUS configuration to use. For example, a UE may be configured with threeWUS configurations. A serving cell may use first WUS configuration, andwhen the UE moves to a new cell (without realising it), the UE willinitially continue to attempt to detect for the first WUS. This may betransmitted by the new (neighbouring) cell (e.g. as requested by the MMEor X2 signalling from the serving cell). In this case the first WUSsignalling transmitted by the new cell may include an indication (e.g.using approach of including additional data as discussed above) for theUE to switch to using the second WUS configuration. The UE can thenproceed with using the second WUS configuration. That is, in thisembodiment, the WUS termination criterion is explicitly indicated in theWUS.

Thus there has been described a method of operating a terminal device ina wireless telecommunications system comprising the terminal device anda plurality of network access nodes, wherein the method comprises:establishing first wake-up signalling configuration information for afirst network access node, wherein the first wake-up signallingconfiguration information comprises an indication of a first wake-upsignalling format to be transmitted by the first network access node inadvance of transmitting a paging message; establishing second wake-upsignalling configuration information for a second network access node,wherein the second wake-up signalling configuration informationcomprises an indication of a second wake-up signalling format to betransmitted by the second network access node in advance of transmittinga paging message; and monitoring for signalling transmitted by the firstnetwork access node in accordance with the first wake-up signallingformat and monitoring for signalling transmitted by the second networkaccess node in accordance with the second wake-up signalling format, andseeking to decode a subsequent paging message in response to detectingwake-up signalling in accordance with either the first wake-upsignalling format or the second wake-up signalling format.

There has also been described a method of operating a first networkaccess node in a wireless telecommunications system comprising aterminal device and a plurality of network access nodes, wherein themethod comprises: establishing first wake-up signalling configurationinformation for the first network access node, wherein the first wake-upsignalling configuration information comprises an indication of a firstwake-up signalling format to be transmitted by the first network accessnode in advance of transmitting a paging message; establishing secondwake-up signalling configuration information for a second network accessnode, wherein the second wake-up signalling configuration informationcomprises an indication of a second wake-up signalling format to betransmitted by the second network access node in advance of transmittinga paging message; and transmitting to the terminal device an indicationof the first and second wake-up signalling configuration information.

It will be appreciated that while the present disclosure has in somerespects focused on implementations in an LTE-based and/or 5G networkfor the sake of providing specific examples, the same principles can beapplied to other wireless telecommunications systems. Thus, even thoughthe terminology used herein is generally the same or similar to that ofthe LTE and 5G standards, the teachings are not limited to the presentversions of LTE and 5G and could apply equally to any appropriatearrangement not based on LTE or 5G and/or compliant with any otherfuture version of an LTE, 5G or other standard.

It may be noted various example approaches discussed herein may rely oninformation which is predetermined/predefined in the sense of beingknown by both the base station and the terminal device. It will beappreciated such predetermined/predefined information may in general beestablished, for example, by definition in an operating standard for thewireless telecommunication system, or in previously exchanged signallingbetween the base station and terminal devices, for example in systeminformation signalling, or in association with radio resource controlsetup signalling. That is to say, the specific manner in which therelevant predefined information is established and shared between thevarious elements of the wireless telecommunications system is not ofprimary significance to the principles of operation described herein. Itmay further be noted various example approaches discussed herein rely oninformation which is exchanged/communicated between various elements ofthe wireless telecommunications system and it will be appreciated suchcommunications may in general be made in accordance with conventionaltechniques, for example in terms of specific signalling protocols andthe type of communication channel used, unless the context demandsotherwise. That is to say, the specific manner in which the relevantinformation is exchanged between the various elements of the wirelesstelecommunications system is not of primary significance to theprinciples of operation described herein.

Further particular and preferred aspects of the present invention areset out in the accompanying independent and dependent claims. It will beappreciated that features of the dependent claims may be combined withfeatures of the independent claims in combinations other than thoseexplicitly set out in the claims.

Thus, the foregoing discussion discloses and describes merely exemplaryembodiments of the present invention. As will be understood by thoseskilled in the art, the present invention may be embodied in otherspecific forms without departing from the spirit or essentialcharacteristics thereof. Accordingly, the disclosure of the presentinvention is intended to be illustrative, but not limiting of the scopeof the invention, as well as other claims. The disclosure, including anyreadily discernible variants of the teachings herein, define, in part,the scope of the foregoing claim terminology such that no inventivesubject matter is dedicated to the public.

Respective features of the present disclosure are defined by thefollowing numbered paragraphs:

Paragraph 1. A method of operating a terminal device in a wirelesstelecommunications system comprising the terminal device and a pluralityof network access nodes, wherein the method comprises: establishingfirst wake-up signalling configuration information for a first networkaccess node, wherein the first wake-up signalling configurationinformation comprises an indication of a first wake-up signalling formatto be transmitted by the first network access node in advance oftransmitting a paging message; establishing second wake-up signallingconfiguration information for a second network access node, wherein thesecond wake-up signalling configuration information comprises anindication of a second wake-up signalling format to be transmitted bythe second network access node in advance of transmitting a pagingmessage; and monitoring for signalling transmitted by the first networkaccess node in accordance with the first wake-up signalling format andmonitoring for signalling transmitted by the second network access nodein accordance with the second wake-up signalling format, and seeking todecode a subsequent paging message in response to detecting wake-upsignalling in accordance with either the first wake-up signalling formator the second wake-up signalling format.

Paragraph 2. The method of paragraph 1, wherein the terminal deviceestablishes the first and second wake-up signalling configurationinformation by receiving an indication of the first and second wake-upsignalling configuration information from the first network access node.

Paragraph 3. The method of paragraph 2, wherein the indication of thefirst and second wake-up signalling configuration information isreceived from the first network access node in system informationbroadcast, SIB, signalling transmitted by the first network access node.

Paragraph 4. The method of paragraph 2, wherein the indication of thefirst and second wake-up signalling configuration information isreceived from the first network access node in radio resource control,RRC, signalling transmitted by the first network access node.

Paragraph 5. The method of any of paragraphs 1 to 4, wherein theterminal device establishes the first and second wake-up signallingconfiguration information in accordance using a predefined mappingbetween different combinations of an identifier for the terminal deviceand an identifier for the respective network access nodes and differentwake-up signalling configuration information.

Paragraph 6. The method of any of paragraphs 1 to 5, wherein theterminal device establishes the first and second wake-up signallingconfiguration information when attached to the first network accessnode, and then in response to detecting wake-up signalling in accordancewith the second wake-up signalling format seeks to decode systeminformation broadcast, SIB, signalling transmitted by the second networkaccess node.

Paragraph 7. The method of any of paragraphs 1 to 6, wherein theterminal device establishes the first and second wake-up signallingconfiguration information when attached to the first network accessnode, and then in response to detecting wake-up signalling in accordancewith the second wake-up signalling format performs a cellselection/reselection procedure.

Paragraph 8. The method of any of paragraphs 1 to 7, wherein monitoringfor signalling transmitted by the first network access node inaccordance with the first wake-up signalling format and monitoring forsignalling transmitted by the second network access node in accordancewith the second wake-up signalling format, comprises monitoring forsignalling transmitted by the first network access node in accordancewith the first wake-up signalling format during a first time periodwithout monitoring for signalling transmitted by the second networkaccess node in accordance with the second wake-up signalling format.

Paragraph 9. The method of paragraph 8, wherein monitoring forsignalling transmitted by the second network access node in accordancewith the second wake-up signalling format is performed during a secondtime period which follows the first time period.

Paragraph 10. The method of paragraph 9, wherein the first time periodends in response to the terminal device receiving signalling transmittedby the second network access node in accordance with the first wake-upsignalling format with an indication this signalling is from the secondnetwork access node and not from the first network access node.

Paragraph 11. The method of paragraph 9 or 10, wherein the second timeperiod is longer than the first time period.

Paragraph 12. The method of any of paragraphs 1 to 11, furthercomprising the terminal device performing a cell selection/reselectionprocedure after not detecting wake-up signalling in either one or bothof the first and second time periods.

Paragraph 13. The method of any of paragraphs 1 to 12, whereinmonitoring for signalling transmitted by the first network access nodein accordance with the first wake-up signalling format and monitoringfor signalling transmitted by the second network access node inaccordance with the second wake-up signalling format are performed atthe same time.

Paragraph 14. The method of any of paragraphs 1 to 13, wherein the firstwake-up signalling format is a dedicated wake-up signalling format forthe first network access node and the second wake-up signalling formatis a common wake-up signalling format for a plurality of network accessnodes including the second network access node.

Paragraph 15. The method of any of paragraphs 1 to 14, furthercomprising determining after a time period of monitoring for signallingtransmitted by the first network access node in accordance with thefirst wake-up signalling format and monitoring for signallingtransmitted by the second network access node in accordance with thesecond wake-up signalling format that at least one of the first andsecond wake-up signalling configuration information is no longer valid,and establishing updated wake-up signalling configuration information inresponse thereto.

Paragraph 16. The method of any of paragraphs 1 to 15, whereindetermining that at least one of the first and second wake-up signallingconfiguration information is no longer valid comprises determining apredefined validity period for the at least one of the first and secondwake-up signalling configuration information has expired.

Paragraph 17. The method of any of paragraphs 1 to 16, whereindetermining that at least one of the first and second wake-up signallingconfiguration information is no longer valid comprises receiving anindication from one of the plurality of network access nodes thatpredefined validity period for the at least one of the first and secondwake-up signalling configuration information has expired.

Paragraph 18. The method of any of paragraphs 1 to 17, furthercomprising establishing further wake-up signalling configurationinformation for at least one further network access node, wherein thefurther wake-up signalling configuration information comprises anindication of at least one further wake-up signalling format to betransmitted by respective ones of the at least one further networkaccess node in advance of transmitting a paging message; and monitoringfor signalling transmitted by the at least one further network accessnode in accordance with the at least one further wake-up signallingformat, and seeking to decode a subsequent paging message in response todetecting wake-up signalling in accordance with the at least one furtherwake-up signalling format.

Paragraph 19. A terminal device for use in a wireless telecommunicationssystem comprising the terminal device and a plurality of network accessnodes, wherein the terminal device comprises controller circuitry andtransceiver circuitry configured to operate together such that theterminal device is operable to: establish first wake-up signallingconfiguration information for a first network access node, wherein thefirst wake-up signalling configuration information comprises anindication of a first wake-up signalling format to be transmitted by thefirst network access node in advance of transmitting a paging message;establish second wake-up signalling configuration information for asecond network access node, wherein the second wake-up signallingconfiguration information comprises an indication of a second wake-upsignalling format to be transmitted by the second network access node inadvance of transmitting a paging message; and monitor for signallingtransmitted by the first network access node in accordance with thefirst wake-up signalling format and monitoring for signallingtransmitted by the second network access node in accordance with thesecond wake-up signalling format, and seek to decode a subsequent pagingmessage in response to detecting wake-up signalling in accordance witheither the first wake-up signalling format or the second wake-upsignalling format. 20. Circuitry for a terminal device for use in awireless telecommunications system comprising the terminal device and aplurality of network access nodes, wherein the circuitry comprisescontroller circuitry and transceiver circuitry configured to operatetogether such that the circuitry is operable to: establish first wake-upsignalling configuration information for a first network access node,wherein the first wake-up signalling configuration information comprisesan indication of a first wake-up signalling format to be transmitted bythe first network access node in advance of transmitting a pagingmessage; establish second wake-up signalling configuration informationfor a second network access node, wherein the second wake-up signallingconfiguration information comprises an indication of a second wake-upsignalling format to be transmitted by the second network access node inadvance of transmitting a paging message; and monitor for signallingtransmitted by the first network access node in accordance with thefirst wake-up signalling format and monitoring for signallingtransmitted by the second network access node in accordance with thesecond wake-up signalling format, and seek to decode a subsequent pagingmessage in response to detecting wake-up signalling in accordance witheither the first wake-up signalling format or the second wake-upsignalling format.

Paragraph 21. A method of operating a first network access node in awireless telecommunications system comprising a terminal device and aplurality of network access nodes, wherein the method comprises:establishing first wake-up signalling configuration information for thefirst network access node, wherein the first wake-up signallingconfiguration information comprises an indication of a first wake-upsignalling format to be transmitted by the first network access node inadvance of transmitting a paging message; establishing second wake-upsignalling configuration information for a second network access node,wherein the second wake-up signalling configuration informationcomprises an indication of a second wake-up signalling format to betransmitted by the second network access node in advance of transmittinga paging message; and transmitting to the terminal device an indicationof the first and second wake-up signalling configuration information.

Paragraph 22. The method of paragraph 21, wherein establishing secondwake-up signalling configuration information for the second networkaccess node comprises receiving an indication of the second wake-upsignalling configuration information from the second network accessnode.

Paragraph 23. The method of paragraph 21, further comprisingcommunicating an indication of the first wake-up signallingconfiguration information to the second network access node.

Paragraph 24. The method of paragraph 21 or 22, wherein the indicationof the first and second wake-up signalling configuration information istransmitted to the terminal device in system information broadcast, SIB,signalling transmitted by the first network access node.

Paragraph 25. The method of any of paragraphs 21 to 24, wherein theindication of the first and second wake-up signalling configurationinformation is transmitted to the terminal device in radio resourcecontrol, RRC, signalling transmitted by the first network access node.

Paragraph 26. The method of any of paragraphs 21 to 25, furthercomprising the first network access node receiving from a mobilemanagement entity for the wireless telecommunications system a pagingrequest message for the terminal device, and transmitting wake-upsignalling for the terminal device in accordance with the first wake-upsignalling format and subsequently transmitting a paging message for theterminal device.

Paragraph 27. A first network access node for use in a wirelesstelecommunications system comprising a terminal device and a pluralityof network access nodes, wherein the first network access node comprisescontroller circuitry and transceiver circuitry configured to operatetogether such that the first network access node is operable to:establish first wake-up signalling configuration information for thefirst network access node, wherein the first wake-up signallingconfiguration information comprises an indication of a first wake-upsignalling format to be transmitted by the first network access node inadvance of transmitting a paging message;

establish second wake-up signalling configuration information for asecond network access node, wherein the second wake-up signallingconfiguration information comprises an indication of a second wake-upsignalling format to be transmitted by the second network access node inadvance of transmitting a paging message; and transmit to the terminaldevice an indication of the first and second wake-up signallingconfiguration information.

Paragraph 28. Circuitry for a first network access node for use in awireless telecommunications system comprising a terminal device and aplurality of network access nodes, wherein the circuitry comprisescontroller circuitry and transceiver circuitry configured to operatetogether such that the circuitry is operable to: establish first wake-upsignalling configuration information for the first network access node,wherein the first wake-up signalling configuration information comprisesan indication of a first wake-up signalling format to be transmitted bythe first network access node in advance of transmitting a pagingmessage; establish second wake-up signalling configuration informationfor a second network access node, wherein the second wake-up signallingconfiguration information comprises an indication of a second wake-upsignalling format to be transmitted by the second network access node inadvance of transmitting a paging message; and transmit to the terminaldevice an indication of the first and second wake-up signallingconfiguration information.

REFERENCES

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The invention claimed is:
 1. A method of operating a network access node in a wireless telecommunications system comprising a terminal device and a plurality of network access nodes, wherein the method comprises: establishing first wake-up signalling configuration information, wherein the first wake-up signalling configuration information comprises an indication of a first wake-up signalling format to be transmitted in advance of transmitting a paging message; establishing second wake-up signalling configuration information, wherein the second wake-up signalling configuration information comprises an indication of a second wake-up signalling format to be transmitted in advance of transmitting a paging message; and transmitting to the terminal device an indication of the first and second wake-up signalling configuration information.
 2. The method of claim 1, wherein establishing second wake-up signalling configuration information comprises receiving an indication of the second wake-up signalling configuration information from a second network access node.
 3. The method of claim 1, further comprising: communicating an indication of the first wake-up signalling configuration information to a second network access node.
 4. The method of claim 1, wherein the indication of the first and second wake-up signalling configuration information is transmitted to the terminal device in system information broadcast (SIB) signalling transmitted by the network access node.
 5. The method of claim 1, wherein the indication of the first and second wake-up signalling configuration information is transmitted to the terminal device in radio resource control (RRC) signalling transmitted by the network access node.
 6. The method of claim 1, further comprising: the network access node receiving from a mobile management entity for the wireless telecommunications system a paging request message for the terminal device, and transmitting wake-up signalling for the terminal device in accordance with the first wake-up signalling format and subsequently transmitting a paging message for the terminal device.
 7. A network access node for use in a wireless telecommunications system comprising a terminal device and a plurality of network access nodes, wherein the network access node comprises: circuitry configured to establish first wake-up signalling configuration information, wherein the first wake-up signalling configuration information comprises an indication of a first wake-up signalling format to be transmitted in advance of transmitting a paging message; establish second wake-up signalling configuration information, wherein the second wake-up signalling configuration information comprises an indication of a second wake-up signalling format to be transmitted in advance of transmitting a paging message; and transmit to the terminal device an indication of the first and second wake-up signalling configuration information.
 8. The network access node of claim 7, wherein the circuitry is configured to establish the second wake-up signalling configuration information based on an indication of the second wake-up signalling configuration received information from a second network access node.
 9. The network access node of claim 7, wherein the circuitry is configured to communicate an indication of the first wake-up signalling configuration information to a second network access node.
 10. The network access node of claim 7, wherein the circuitry is configured to transmit the indication of the first and second wake-up signalling configuration information to the terminal device in system information broadcast (SIB) signalling transmitted by the network access node.
 11. The network access node of claim 7, wherein the circuitry is configured to transmit the indication of the first and second wake-up signalling configuration information to the terminal device in radio resource control (RRC) signalling transmitted by the network access node.
 12. The network access node of claim 7, wherein the circuitry is configured to: receive, from a mobile management entity for the wireless telecommunications system a paging request message for the terminal device; and transmit wake-up signalling for the terminal device in accordance with the first wake-up signalling format and subsequently transmit a paging message for the terminal device.
 13. Circuitry for a network access node for use in a wireless telecommunications system comprising a terminal device and a plurality of network access nodes, wherein circuitry is configured to: establish first wake-up signalling configuration information, wherein the first wake-up signalling configuration information comprises an indication of a first wake-up signalling format to be transmitted in advance of transmitting a paging message; establish second wake-up signalling configuration information, wherein the second wake-up signalling configuration information comprises an indication of a second wake-up signalling format to be transmitted in advance of transmitting a paging message; and transmit to the terminal device an indication of the first and second wake-up signalling configuration information.
 14. The circuitry of claim 13, wherein the circuitry is configured to establish the second wake-up signalling configuration information based on an indication of the second wake-up signalling configuration received information from a second network access node.
 15. The circuitry of claim 13, wherein the circuitry is configured to communicate an indication of the first wake-up signalling configuration information to a second network access node.
 16. The circuitry of claim 13, wherein the circuitry is configured to transmit the indication of the first and second wake-up signalling configuration information to the terminal device in system information broadcast (SIB) signalling transmitted by the network access node.
 17. The circuitry of claim 13, wherein the circuitry is configured to transmit the indication of the first and second wake-up signalling configuration information to the terminal device in radio resource control (RRC) signalling transmitted by the network access node.
 18. The circuitry of claim 13, wherein the circuitry is configured to: receive, from a mobile management entity for the wireless telecommunications system a paging request message for the terminal device; and transmit wake-up signalling for the terminal device in accordance with the first wake-up signalling format and subsequently transmit a paging message for the terminal device. 